Samples, for example bodily fluids such as blood or urine, are frequently analyzed using analysis devices in which the samples to be analyzed are located on a test element and may react with one or more reagents on the test element in a test area before they are analyzed. The optical, in particular photometric evaluation, and the electrochemical evaluation of test elements represent the most usual methods for rapid determination of the concentration of analytes in samples. Analysis systems with test elements for sample analysis are generally used in the field of analysis, environmental analysis and in particular in the field of medical diagnosis. Particularly in the field of blood glucose diagnosis from capillary blood, test elements which are evaluated photometrically or electrochemically play a major role.
There are various forms of test elements. By way of example, essentially square platelets are known, which are also referred to as slides, in whose center a multilayer test area is located. Diagnostic test elements which are in the form of strips are referred to as test strips. The prior art extensively describes test elements, for example in the documents DE-A 197 53 847, EP-A 0 821 233, EP-A 0 821 234 or WO 97/02487, the disclosures of which are hereby incorporated herein by reference in their entireties. The present invention relates to test elements in any desired form, including test elements in the form of strips.
Test element analysis systems which contain a test element holder for positioning of the test element in a measurement position, and a measurement and evaluation device for carrying out a measurement and for determining an analysis result resulting from this are known from the prior art for analytical investigation of a sample on a test element, including WO 00/19185, the disclosure of which is hereby incorporated by reference herein in its entirety.
Further analysis devices are known, for example, from EP 0 618 443 A1 or WO 01/48461 A1, the disclosures of which are hereby incorporated by reference herein in their entireties.
Another exemplary system is the ACCU-CHEK® Compact Plus blood glucose analysis system developed by Roche Diagnostics which measures the blood glucose value using the photometric measurement principle. A color change in a test area on a test element which has previously been wetted with the blood of a patient is in this case detected by an optical measurement module and is electronically converted in the device to a value which is proportional to the blood glucose. The measurement process is started using a switch-on button. A motor in a motor module then rotates the drum, which is used as a supply container, with the test elements around a chamber of the supply container further, and a second motor uses a push rod to push a test element out, so that it can be wetted with blood by the user, outside the device. During the process, the test element remains so far in the analysis device that the test area with the indicator chemistry is positioned over the measurement optics in the measurement module. The measurement optics comprise two diodes, a photocell and a lens. The change in the diffuse reflection is converted by the photocell to a signal current which is processed by an electronic circuit on a printed circuit board, and is displayed as blood glucose value on an LC display. The measurement process is ended by operating the switch-on button again, pushing out the test element and switching the analysis device off. The measurement and drive electronics are supplied with a total voltage of about 3 V from two batteries. In contrast to comparable analysis devices, into which, for example, test elements are supplied from the outside and individual intermediate states have to be operated manually, this device has greater functional integration. Seventeen individual test elements are mounted in the supply container, which is in the form of a drum, and the specification for the test elements is identified automatically by means of a barcode reader in the analysis device. A change in the test element magazine, which is in the form of a drum, is detected via a switch on the housing upper part after opening and closing of the test element magazine holder cover. The required states, such as rotation of the test element magazine through one step and various holding positions during the forward movement of the test element are signaled via sliding contacts and dynamically sprung switching contacts to the electronics on the printed circuit board, without any control function being required by the user. In this context, “dynamically sprung” means force loading and unloading and repeated linear movement during operation. The core of the analysis device for carrying out these electromechanical functions is formed by the motor module. This is used, inter alia, to hold the drive motors and the transmission board. The printed circuit board is screwed to the motor module. For this purpose, all the other contacts between these two assemblies are in the form of detachable static spring contents, for example the contacts for the electrical power supply for the drive motors and for the measurement module. In this context, “statically sprung” means single force loading and linear movement during device assembly. The printed circuit board has four layers, because of the numerous functions which are integrated in the device and must be controlled by the device software.
The analysis devices known in the prior art have a multiplicity of components which make electrical contact. For example, sprung contacts, plug-in contacts, solder contacts or sliding contacts which connect the assemblies printed circuit board, motor module, measurement module, drum cover switch, barcode reader and LCD to one another, are known from the Roche Diagnostics Accu-Chek® Compact Plus. Metallic stamped and bent parts are used for this purpose in the prior art, which must be positioned and mounted on the individual assemblies, thus resulting in a large number of individual components, a large amount of assembly effort, and long tolerance chains. Furthermore, the design freedom of the component which makes electrical contact is restricted when using stamped and bent parts, and often requires larger than desired form factors for the analysis device as a result of the larger and more numerous components.
The object of the present invention is therefore to avoid the disadvantages of the prior art and to provide an analysis device for analysis of a sample on a test element with components which make electrical contact, by ensuring that reliable electrical contact is made with a smaller number of individual parts to be fitted.